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1

Is the indentation made from spaces or tabs? Is it consistent throughout?
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DerfKMay 12 '12 at 6:10

use appropriate file handle to write.You opened WRITE_FILE handle But,you wrote to the(unopened file handle) WRITEFILE.It doesn't make any sense.Be pratice to use use strict and use warning or -w .
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satMay 12 '12 at 7:12

I have you seen the output.why the first line come like this. :cerycium:cerycia .That means,first character is : (colon) .I think you have to add some condition in else block.That is,if(length($prefix) == 0) { $_ = "$prefix"; } else {$_= "$prefix:$_";}.
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satMay 12 '12 at 8:14

I see correct output as expected. You can check your input file.
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TheCottonSilkMay 12 '12 at 9:26